1. Department of Gastroenterology, Mayo Clinic, Jacksonville, Florida, USA
2. Division of Surgical Pathology and Gastrointestinal Pathology Service, Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
3. Division of Gastroenterology and Hepatology, University of Colorado Denver, Denver, Colorado, USA
4. Academic Medical Center, Amsterdam, The Netherlands
5. Kansas University Medical Center and Department of Veterans Affairs Medical Center, Kansas City, Kansas, USA
6. Klinikum rechts der Isar, Technical University of Munich, Munich, Germany